LOCAL ADAPTATION IN TWO SUBSPECIES OF AN ANNUAL PLANT: IMPLICATIONS FOR MIGRATION AND GENE FLOW

Area of Science:

• Ecology
• Evolutionary Biology
• Plant Science

Background:

• Plant populations frequently exhibit adaptation to local environmental conditions.
• Understanding local adaptation is crucial for predicting species' responses to environmental change.

Purpose of the Study:

• To investigate local adaptation in two subspecies of Gilia capitata.
• To quantify subspecies performance differences across coastal and inland environments.

Main Methods:

• Employed standard reciprocal transplant techniques over three years.
• Assessed four fitness components: seedling emergence, vegetative size, flowering probability, and inflorescence production.
• Utilized cohort life table analysis to compare replacement rates (R₀).

Main Results:

• Site-by-subspecies interactions revealed local adaptation, with natives outperforming immigrants.
• The disadvantage for immigrants was more pronounced at the coastal site compared to the inland site.
• Life table analysis indicated a severe demographic disadvantage for immigrants at the coastal site.

Conclusions:

• Local adaptation in Gilia capitata is evident, particularly in the coastal environment.
• Integrating multiple fitness components is essential for accurately assessing the magnitude of local adaptation.
• Differential selection pressures exist between coastal and inland sites, impacting subspecies performance.